THE   MOON 

BY 

OLIVER  C.  FARRINGTON 
Curator  of  Geology 


Geology 
Leaflet  6 


FIELD  MUSEUM  OF  NATURAL  HISTORY 
CHICAGO 

1925 


LIST  OF  GEOLOGICAL  LEAFLETS  ISSUED  TO  DATE 

Model  of  an  Arizona  Gold  Mine $  .10 

Models  of  Blast  Furnaces  for  Smelting  Iron    .        .10 
Amber — Its  Physical  Properties  and 

Geological  Occurrence 10 

Meteorites 10 

Soils 10 

The  Moon 10 

D.  C.  DA  VIES,  Director 


FIELD  MUSEUM  OF  NATURAL  HISTORY 
CHICAGO.  U.  S.  A. 


No. 

1. 

No. 

2. 

No. 

3. 

No. 

4. 

No. 

5. 

No. 

6. 

PHOTOGRAPH  OF  MODEL  IN  RELIEF  OF  THE  VISIBLE  HEMISPHERE  OF  THE  MOON.      HALL  35. 
The  model  is  19  feet  in  diameter. 


I 


Field  Museum  of  Natural  History 

DEPARTMENT  OF  GEOLOGY 
Chicago,  1925 

Leaflet  Number  6 

THE  MOON 

Except  for  occasional  comets  and  meteors,  the 
Moon  is  the  celestial  body  nearest  the  Earth.  Its  mean 
distance  from  the  Earth  is  237,640  miles,  but  as  it 
moves  in  an  elliptical  orbit,  it  has  at  one  point  a 
remoteness  of  253,263  miles  and  opposite  to  this 
one  of  221,436  miles.  The  diameter  of  the  Moon  is 
about  one-fourth  that  of  the  Earth,  or  2,160  miles, 
and  its  volume  is  1/49  that  of  the  Earth.  The  mass  of 
the  Moon  (volume  multiplied  by  density)  is  1/81  and 
the  density  3/5  that  of  the  Earth.  The  period  of  the 
Moon's  revolution  about  the  Earth  is  27  days,  7  hours, 
43  minutes  and  III/2  seconds.  As  its  period  of  rota- 
tion on  its  axis  is  the  same,  only  one  side  of  the  Moon 
is  ever  seen  from  the  Earth.  Since,  however,  the 
Moon's  axis  is  inclined  about  83°  to  the  plane  of  its 
orbit,  we  sometimes  see  a  little  distance  beyond  each 
of  its  poles,  and,  since  the  rate  of  motion  of  the  Moon 
in  its  orbit  varies  slightly,  we  sometimes  see  a  little 
beyond  the  eastern  and  western  edges  of  the  hemi- 
sphere. The  total  result  of  these  librations,  as  they 
are  called,  is  to  make  four-sevenths  of  the  Moon's  sur- 
face visible  to  us.  Of  the  remaining  three-sevenths, 
nothing  is  known.  So  far  as  is  known,  the  Moon  is 
not  flattened  at  the  poles. 

Owing  to  its  slow  rotation  on  its  axis,  the  Moon's 
day  has  a  length  of  291/2  of  our  days.  Each  portion 
of  its  surface  is  therefore  exposed  to  or  shielded  from 
the  light  of  the  Sun  for  a  fortnight  continuously. 

[69] 


2  Field  Museum  of  Natural  History 

The  Moon  has  no  atmosphere.  Hence,  it  can  have 
no  diffused  Hght,  and  nothing  can  be  seen  on  it  except 
where  the  Sun's  rays  shine  directly.  "If  a  man  stepped 
into  the  shadow  of  a  lunar  crag,"  says  Todd,  "he  would 
instantly  become  invisible.  For  a  similar  reason,  no 
sound,  however  loud,  can  be  heard  on  the  Moon.  The 
rolhng  of  a  rock  down  the  wall  of  a  lunar  crater,  will 
be  known  only  by  the  tremor  it  produces."  Moreover, 
changes  of  temperature  on  the  Moon  are  rapid  and 
violent.  Where  the  Sun's  rays  strike,  a  temperature 
about  that  of  boiling  water  is  believed  to  be  reached, 
while  in  unilluminated  portions  it  is  thought  to  go  as 
low  as  100°  below  zero. 

The  force  of  gravity  upon  the  surface  of  the  Moon 
is  only  1/6  of  that  on  the  Earth.  Therefore,  a  man 
weighing  150  pounds  on  the  Earth,  would  weigh  only 
25  pounds  on  the  Moon,  and  the  same  muscular  energy 
by  which  he  could  jump  6  feet  on  the  Earth  would 
carry  him  a  distance  of  36  feet  on  the  Moon.  On  the 
Earth  a  body  falls  16  feet  in  one  second;  on  the  Moon 
only  2.6  feet  in  the  same  time. 

The  surface  of  the  Moon  is  made  up  of  mountains, 
valleys  and  plains,  resembling  in  general  appearance 
those  of  the  Earth.  As  a  whole,  however,  the  surface 
of  the  Moon  is  much  more  uneven  than  that  of  the 
Earth.  Some  of  the  mountains  of  the  Moon  have  a 
height  of  over  20,000  feet.  As  there  is  no  sea-level  to 
measure  from,  this  figure  expresses  height  above  the 
surrounding  surface,  it  being  determined  by  the  length 
of  the  shadows  cast  by  the  mountains. 

In  order  to  represent  in  a  vivid  and  accurate 
manner  the  character  and  appearance  of  the  Moon's 
surface,  the  construction  of  a  large  model  of  the  Moon 
was  undertaken  a  number  of  years  ago  by  Th.  Dickert, 
Curator  of  the  Natural  History  Museum  of  Bonn,  Ger- 
many and  Dr.  J.  F.  Julius  Schmidt,  Director  of  the 
Observatory  of  Athens,  Greece  and  an  eminent  seleno- 

[60] 


The  Moon  3 

grapher.  The  model  was  presented  to  the  Museum 
by  the  late  Lewis  Reese  of  Chicago,  and  is  installed  at 
the  west  end  of  Hall  35  of  the  Museum.  The  model  is 
19.2  feet  in  diameter,  and  is  by  far  the  largest  and 
most  elaborate  representation  of  the  Moon's  surface 
ever  made.  Its  horizontal  scale  is  1 : 600,000,  one  inch 
on  the  model  equaling  9^^miles  on  the  surface  of 
the  Moon,  and  its  vertical  scale  is  1:200,000,  one  inch 
equaling  3-L^-miles  on  the  Moon. 

Some  characteristic  features  of  the  Moon's  sur- 
face which  are  especially  well  illustrated  on  the  model 
are  the  following: 

1.  GRAY  PLAINS  or  "SEAS."  These  are  the 
darker  portions  of  the  Moon's  surface  as  it  is  seen 
with  the  naked  eye.  They  were  thought  by  earlier 
observers  to  be  seas  and  were  so  named.  We  now 
know,  however,  that  there  is  no  water  on  the  Moon's 
surface  and  that  the  so-called  "seas"  are  really  low- 
land plains,  some  of  them  of  vast  extent.  The  Oceanus 
Procellarum,  for  instance,  covers  an  area  of  90,000 
square  miles.  As  seen  from  the  Earth,  the  plains 
show  a  gray-green  color,  often  of  varying  intensity 
and  sometimes  a  little  bluish  in  portions.  The  bright- 
est green  color  is  shown  by  the  area  known  as  Mare 
Serenitatis.  Though  appearing  perfectly  level,  a  close 
study  shows  that  these  plains  have  undulating  sur- 
faces. They  occupy  about  one-third  of  the  visible  sur- 
face of  the  Moon. 

2.  MOUNTAINS  and  HIGHLANDS.  These  con- 
stitute the  bright  portions  of  the  Moon's  surface  as 
it  is  seen  with  the  naked  eye. 

Although  these  elevated  areas  are  conveniently 
called  mountains,  Shaler  has  drawn  attention  to  the 
fact  that  they  are  unlike  those  on  the  Earth  since 

[61] 


4  Field  Museum  of  Natural  History 

they  lack  features  due  to  erosion  and  there  is  absence 
of  order  in  their  association.  The  average  declivity  of 
their  slopes  is  also  much  greater  than  that  of  the 
mountains  on  the  Earth.  It  has  been  estimated  that 
the  average  angle  of  the  lunar  surface  to  its  horizon 
is  52°,  while  on  the  Earth  it  does  not  amount  to  more 
than  one-tenth  of  that  figure.  This  difference  is  prob- 
ably due  to  the  lack  of  water  on  the  Moon,  the  work 
of  which  on  the  Earth  tends  continually  to  reduce 
slopes  to  a  level.  Using  the  term  mountains  for  con- 
venience, however,  those  on  the  Moon  may  be  divided 
into  the  following  classes: 

a.  Mountain  Chains.  These  may  have  a  length 
of  80  to  100  miles  and  heights  of  from  5,000  to  17,000 
feet.  As  in  the  case  with  the  mountains  of  the  Earth, 
they  are  usually  steeper  on  one  side  than  on  the  other. 
The  range  called  the  Appenines,  seen  near  the  north 
pole  of  the  Moon,  is  a  good  illustration  of  such  moun- 
tain chains.  Other  ranges  are  the  so-called  Alps  and 
Caucasus.  These  names  were  applied  by  Hevelius,  an 
astronomer  of  Danzig,  who  made  the  first  map  of  the 
Moon  in  1647.  He  gave  to  the  features  of  the  Moon's 
surface  names  of  localities  similar  to  those  on  the 
Earth  which  they  most  resembled.  His  system  was 
largely  abandoned  by  later  astronomers,  however,  the 
later  method  being  to  name  the  different  features  of 
the  Moon  after  celebrated  astronomers  and  philosoph- 
ers. 

b.  Highlands  Surrounded  By  Mountains.  These  are 
partly  with  and  partly  without  well-determined  direc- 
tions. • 

c.  Isolated  Mountains.  These  usually  occur  on 
the  gray  plains.  They  vary  from  4,000  to  7,000  feet 
in  height. 

[62] 


The  Moon  5 

d.  Vein  Mountains.  These  occur  only  on  the  gray 
plains.  They  are  long,  narrow,  contorted  ridges,  usu- 
ally from  700  to  1,000  feet  in  height. 

e.  Circular  Mountains.  These  are  the  most  char- 
acteristic and  peculiar  features  of  the  Moon's  sur- 
face. They  vary  in  size  from  the  so-called  "Walled 
Plains,"  150  to  15  miles  in  diameter,  to  crater  mount- 
ains whose  diameters  range  from  15  miles  down  to  a 
few  hundred  feet.  Thirty-three  thousand  of  these 
crater  mountains  have  been  counted  by  one  astron- 
omer, the  number  increasing  as  the  size  diminishes. 

The  form  of  these  craters  is  that  of  pits,  which 
generally  have  ring-like  walls  about  them.  These 
wails  slope  very  steeply  to  a  central  cavity  and  more 
gently  toward  the  surrounding  country.  In  all  these 
pits,  as  pointed  out  by  Shaler,  except  those  of  the 
smallest  size,  and  possibly  in  these,  also,  there  is,  with- 
in the  ring  wall  and  at  a  considerable  though  variable 
depth  below  its  summit,  a  nearly  flat  floor,  which  often 
has  a  central  pit  of  small  size  or,  in  its  place,  a 
steep  cone.  When  this  floor  is  more  than  20  miles 
in  diameter,  and  in  increasing  numbers  as  it  is  wider, 
there  are  generally  other  pits  and  cones  irregularly 
scattered  upon  it.  Thus,  within  the  ring  called  Plato, 
which  is  about  60  miles  in  diameter,  there  are  some 
scores  of  these  lesser  pits.  On  the  interior  of  the 
ring  walls  of  the  pits  over  10  miles  in  diameter,  there 
are  usually  more  or  less  distinct  terraces,  which  sug- 
gest that  the  material  now  forming  the  solid  floors 
they  inclose  was  once  fluid  and  stood  at  greater  heights 
in  the  pit  than  that  at  which  it  became  permanently 
frozen.  It  is,  indeed,  tolerably  certain  that  the  last 
movement  of  this  material  of  the  floors  was  one  of 
interrupted  subsidence  from  an  originally  greater 
elevation  on  the  outside  of  the  ring  wall.  The  ring 
wall  is  commonly  of  irregular  height,  with  many  peaks. 

[63] 


6  Field  Museum  of  Natural  History 

In  some  places  there  may  be  seen  tongues  or  protru- 
sions of  the  substance  which  forms  the  ring,  as  if  it 
had  flowed  a  short  distance  and  then  had  cooled  with 
steep  slopes.  It  may  also  be  noted:  (a)  that  the  pits 
or  craters  in  many  instances  intersect  each  other, 
showing  that  they  were  not  all  formed  at  the  same 
time,  but  in  succession;  (b)  that  the  larger  of  them 
are  not  found  on  the  plains  (seas)  but  on  the  upland 
and  apparently  the  older  parts  of  the  surface;  and 
(c)  that  the  evidence  from  the  intersections  clearly 
indicates  that  the  larger  of  these  structures  are  pre- 
vailingly the  older  and  that  in  general  the  smallest 
were  the  latest  formed.  In  other  words,  says  Shaler, 
whatever  was  the  nature  of  the  action  involved  in 
the  production  of  the  craters,  its  energy  diminished 
with  time,  until  in  the  end  it  could  no  longer  break  the 
crust.  These  features  indicate  that  the  surface  of 
the  Moon  has  been  subject  to  forces  similar  to  those 
which  produce  volcanoes  on  the  Earth,  and  it  is  there- 
fore customary  to  refer  to  the  crater-like  mountains 
of  the  Moon  as  volcanoes.  As  the  parallel  cannot  be 
drawn  too  closely,  however,  Shaler  has  urged  that  the 
term  vulcanoids,  meaning  volcano-like,  be  applied  to 
these  mountains. 

3.  RILLS  or  CLEFTS.  These  are  small,  deep, 
ditch-like  furrows  to  be  found  over  various  parts  of 
the  Moon's  surface.  Their  course  seems  quite  in- 
dependent of  the  surface  topography,  for  they  traverse 
mountains  and  plains  with  equal  facility.  They  are 
without  doubt  the  latest  formation  on  the  Moon  and 
some  of  them  may  have  had  their  origin  in  modern 
times. 

4.  BRIGHT  STREAKS.  These  radiate  prom- 
inently from  many  of  the  great  craters  of  the  Moon. 
They  are  streaks  of  narrow  width  but  sometimes 
nearly  a  hundred  miles  in  length.    They  are  perhaps 

[64] 


The  Moon  7 

the  most  puzzling  of  all  the  Moon's  features.  They 
have  been  supposed  by  some  observers  to  represent 
lava  flows  whose  surface  reflected  light  more  brilliantly 
than  other  portions  of  the  Moon.  It  is  more  generally 
believed,  however,  that  the  streaks  do  not  represent 
any  independent  elevations,  since  they  run  over  the 
highest  mountains  as  well  as  through  the  deepest 
craters  without  variation. 

GENERAL  OBSERVATIONS. 

The  condition  of  the  Moon's  surface  as  a  whole 
indicates  that  it  has  been  a  theater  of  extraordinary 
volcanic  activity.  In  size  and  number  its  vulcanoids 
far  exceed  the  volcanoes  of  the  Earth.  The  largest 
terrestrial  crater  known  is  that  of  Kilauea  in  the 
Hawaiian  Islands  which  is  2I/2  miles  in  diameter. 
Several  craters  of  the  Moon,  however,  exceed  50  miles 
in  diameter  and  one  measures  II414  miles.  While  the 
absolute  heights  of  the  mountains  of  the  Moon  do  not 
greatly  exceed  those  of  the  Earth,  proportionally  they 
are  much  higher,  since  the  Moon's  diameter  is  only 
one-fourth  that  of  the  Earth.  The  vulcanoids  of  the 
Moon  differ  in  other  respects  from  the  volcanoes  of 
our  globe.  "On  the  Earth  they  are  usually  openings 
on  the  summits  or  sides  of  mountains — on  the  Moon, 
depressions  below  the  adjacent  surface  even  when  it 
is  a  plain  or  valley;  on  the  Earth  the  mass  of  the 
cone  usually  far  exceeds  the  capacity  of  the  crater — 
on  the  Moon  they  are  much  nearer  equality;  on  the 
Earth  they  are  commonly  the  sources  of  long  lava 
streams — on  the  Moon,  traces  of  such  outpourings  are 
rare."     (Webb.) 

DESCRIPTION   OF   INDIVIDUAL   FEATURES. 

(Abridged  from  Nasmyth  and  Carpenter.) 
The  numbers  refer  to  those  on  the  accompanying 
chart. 

[65] 


8  Field  Museum  of  Natural  History 

Copernicus.  147.  This  may  deservedly  be  consid- 
ered one  of  the  grandest  and  most  instructive  of 
lunar  craters.  Though  its  diameter  (46  miles)  is  ex- 
ceeded by  that  of  other  craters,  its  situation  near 
the  center  of  the  lunar  disc  renders  it  so  conspicuous 
as  to  make  it  a  favorite  object  for  observation.  Its 
vast  rampart  rises  to  upwards  of  12,000  feet  above 
the  level  of  the  plateau,  nearly  in  the  center  of  which 
stands  a  magnificent  group  of  cones  attaining  the 
height  of  upwards  of  2400  feet.  The  rampart  is  di- 
vided by  concentric  segmented  terraced  ridges,  which 
present  every  appearance  of  being  enormous  landslips, 
resulting  from  the  crushing  of  their  overloaded  sum- 
mits which  have  slid  down  in  vast  segments  and 
scattered  their  debris  on  the  plateau.  Corresponding 
vacancies  in  the  rampart  may  be  observed  from  whence 
these  prodigious  masses  have  broken  away.  The  same 
may  be  noticed,  to  a  somewhat  modified  degree,  around 
the  exterior  of  the  rampart.  For  upwards  of  70  miles 
around  Copernicus  myriads  of  comparatively  minute 
but  perfectly  formed  craters  can  be  seen.  The  district 
on  the  southeast  side  is  especially  rich  in  them.  Many 
somewhat  radial  ridges  or  spurs  may  be  observed  lead- 
ing away  from  the  exterior  banks  of  the  great  rampart. 
They  appear  to  be  due  to  the  freer  egress  which  the 
extruded  matter  found  near  the  focus  of  disruption. 

Triesnecker.  150.  A  fine  example  of  a  normal 
lunar  volcanic  crater  having  all  the  usual  charac- 
teristic features  in  great  perfection.  Its  diameter  is 
about  20  miles  and  it  possesses  a  good  example  of  the 
central  cone  and  also  of  interior  terracing.  The  most 
notable  feature,  however,  is  the  remarkable  display 
of  cracks  or  chasms  which  may  be  seen  to  the  west 
side  of  it.  Several  of  these  cracks  obviously  diverge 
from  near  the  west  external  bank  of  the  great  crater 
and   they  sub-divide   or   branch   out  as   they   extend 

[66] 


The  Moon  9 

from  the  apparent  point  of  divergence,  while  they  are 
crossed  or  intersected  by  others.  These  cracks  or 
chasms  are  nearly  one  mile  wide  at  their  widest  part 
and  after  extending  for  fully  100  miles  taper  away 
till  they  become  invisible. 

Theophilus.  97.  Cyrillus.  96.  Catharina.  95. 
These  three  magnificent  craters  form  a  conspicuous 
group.  Their  diameters  and  depths  are  as  follows : 
Theophilus,  diameter,  64  miles;  depth  of  interior 
plateau  from  summit  of  crater  wall,  16,000  feet; 
central  cone,  5200  feet  high;  Cyrillus,  diameter,  60 
miles;  depth  of  interior  plateau  from  summit  of 
crater  wall,  15,000  feet;  central  cone,  5800  feet  high; 
Catharina,  diameter,  65  miles;  depth  of  interior  pla- 
teau from  summit  of  crater  wall,  13,000  feet;  center 
of  plateau  occupied  by  a  confused  group  of  minor  crat- 
ers and  debris.  Each  of  these  craters  is  full  of  inter- 
esting details  presenting  in  every  variety  the  char- 
acteristic features  of  the  lunar  volcanoes  and  giving 
unmistakable  evidence  of  the  tremendous  energy 
which  at  some  remote  period  piled  up  such  gigantic 
formations.  The  intrusion  of  Theophilus  within  Cyril- 
lus shows  that  it  is  of  more  recent  formation  than 
the  latter.  The  flanks  of  Theophilus,  especially  on  the 
west  side,  are  studded  with  apparently  minute  craters. 
These  would  be  considered  of  great  size  but  for  the 
enormous  crater  so  near. 

Ptolemy.  111.  Alphons.  110.  Arzachael.  84.  The 
portion  of  the  moon's  surface  which  includes  these 
features,  being  near  the  center  of  the  lunar  disc,  is 
exceptionally  well  placed  for  observation.  Within  this 
area  may  be  seen  every  variety  of  volcanic  craters 
and  a  number  of  other  interesting  forms.  Ptolemy 
belongs  to  the  class  of  walled  plains,  its  ramparts  en- 
closing a  plain  86  miles  in  diameter.     Alphons  and 

[67] 


10  Field  Museum  of  Natural  History 

Arzachael  are  respectively  60  and  55  miles  in  diameter. 
They  have  all  the  distinctive  features  of  lunar  craters, 
viz : — central  cones,  lofty,  ragged  ramparts,  manifesta- 
tions of  landslip  formations  in  the  great  segmental 
terraces  within  their  ramparts  and  minor  craters  in- 
terpolated within  their  plateaus.  A  notable  object 
near  Alphons  is  an  enormous  straight  cliff  traversing 
the  diameter  of  a  low,  ridged,  circular  formation.  This 
great  cliff  is  60  miles  long  and  from  1000  to  2000 
feet  high.  It  is  a  well  known  object  to  lunar  observers 
and  has  been  termed  "The  Railway"  on  account  of 
its  straightness.  The  existence  of  this  remarkable 
cliff  appears  to  be  due  either  to  an  upheaval  or  a  down- 
sinking  of  a  portion  of  the  surface  of  the  circular  area 
across  whose  diameter  it  extends. 

Tycho.  80.  This  magnificent  crater  is  54  miles  in 
diameter  and  upwards  of  16,000  feet  deep  from  the 
highest  ridge  of  the  rampart  to  the  surface  of  the 
plateau.  It  is  one  of  the  most  conspicuous  of  lunar 
craters,  not  so  much  on  account  of  its  dimensions  as 
from  its  occupying  the  great  focus  of  disruption  from 
whence  diverge  those  remarkable  bright  streaks  many 
of  which  may  be  traced  over  1000  miles  of  the  moon's 
surface.  The  interior  of  the  crater  presents  striking 
examples  of  the  concentric,  terrace-like  formations 
that  are  regarded  as  formed  by  landslips. 

Wargentin.  26.  ScHicKARD.  28.  Wargentin  is  an 
object  quite  unique  of  its  kind — a  crater  about  52 
miles  across,  that  to  all  appearance  has  been  filled 
to  the  brim  with  lava  that  has  been  left  to  con- 
solidate. There  are  evidences  of  the  remains  of  a 
rampart,  especially  on  the  southwest  portion  of  the 
rim.  The  general  aspect  of  Wargentin  has  been  com- 
pared to  that  of  a  "thin  cheese."  The  terraced  and 
rutted  exterior  of  the  rampart  has  all  the  details  of  a 

[68] 


The  Moon 


11 


true  crater.  The  surface  of  the  high  plateau  is  marked 
by  a  few  ridges  branching  from  a  point  nearly  in  the 
center. 

Schickard  is  one  of  the  finest  examples  of  a  walled 
plain.  It  is  153  miles  in  diameter.  Within  its  ram- 
part are  16  smaller  craters  and  without,  numberless 
others. 

The  following  are  the  names  of  topographic  fea- 
tures of  the  Moon  which  can  be  located  by  the  cor- 
responding numbers  on  the  accompanying  chart. 


1.  Newton. 

2.  Short. 

3.  Simpelius. 

4.  Manzinus. 

5.  Moretus. 

6.  Gruemberger. 

7.  Casatus. 

8.  Klaproth. 

9.  Wilson. 

10.  Kircher. 

11.  Bettinus. 

12.  Blancanus. 

13.  Clavius. 

14.  Scheiner. 

15.  Zuchius. 

16.  Segner. 

17.  Bacon. 

18.  Nearchus. 

19.  Vlacq. 

20.  Hommel. 

21.  Licetus. 

22.  Maginus. 

23.  Longomon- 

tanus. 

24.  Schiller. 

25.  Phocylides. 

26.  Wargentin. 

27.  Inghirami. 

28.  Schickard. 

29.  Wilhelm  I. 

30.  Tycho. 

31.  Saussure. 

32.  Stoefler. 

33.  Maurolycus. 

34.  Barocius. 

35.  Fabricius. 

36.  Metius. 

37.  Fernelius. 

38.  Heinsius. 


39.  Hainzel. 

40.  Bouvard. 

41.  Piazzi. 

42.  Ramsden. 

43.  Capuanus. 

44.  Cichus. 

45.  Wurzelbauer. 

46.  Gauricus. 

47.  Hell. 

48.  Walter. 

49.  Nonius. 

50.  Riccius. 

51.  Rheita. 

52.  Furnerius. 

53.  Stevinus. 

54.  Hase. 

55.  Snell. 

56.  Borda. 

57.  Neander. 

58.  Piccolomini. 

59.  Pontanus. 

60.  Poisson. 

61.  Aliacensis. 

62.  Werner. 

63.  Pitatus. 

64.  Hesiodus. 

65.  Mercator. 

66.  Vitello. 

67.  Fourier. 

68.  Lagrange. 

69.  Vieta. 

70.  Doppelmayer. 

71.  Campanus. 

72.  Kies. 

73.  Purbach. 

74.  La  Caille. 

75.  Playfair. 

76.  Azophi. 

77.  Sacrobosco. 

[69] 


78.  Fracastorius. 

79.  Santbech. 

80.  Petavius. 

81.  Wilhelm  Hum- 

boldt. 

82.  Polybius. 

83.  Geber. 

84.  Arzachael. 

85.  Thebit. 

86.  Bullialdus. 

87.  Hippalus. 

88.  Cavendish. 

89.  Mersenius. 

90.  Gassendi. 

91.  Lubiniezky. 

92.  Alpetragius. 

93.  Airy, 

94.  Almanon. 

95.  Catharina. 

96.  Cyrillus. 

97.  Theophilus. 

98.  Colombo. 

99.  Vendelinus. 

100.  Langreen, 

101.  Goclenius, 

102.  Guttemberg. 

103.  Isidorus. 

104.  Capella. 

105.  Kant. 

106.  Descartes. 

107.  Abulfeda. 

108.  Parrot. 

109.  Albategnius, 

110.  Alphons. 

111.  Ptolemy, 

112.  Herschel. 

113.  Davy. 

114.  Guerike. 
116,  Bonpland. 


12 


Field  Museum  of  Natural  History 


117.  Lalande. 

118.  Reaumur. 

120.  Letronne. 

121.  Billy. 

122.  Fontana. 

123.  Hansteen. 

124.  Danioiseau. 

125.  Grimaldi. 

126.  Flamsteed. 

127.  Landsberg. 

128.  Moesting. 

129.  Deambrel. 

130.  Taylor. 

131.  Messier. 

132.  Maskelyne. 

133.  Sabine. 

134.  Ritter. 

135.  Godin. 

136.  Soemmering. 

137.  Schroeter. 

138.  Gambart. 

139.  Reinhold. 

140.  Encke. 

141.  Hevelius. 

142.  Riccioli. 

143.  Lohrman. 

144.  Cavalerius. 

145.  Reiner. 

146.  Kepler. 

147.  Copernicus. 

148.  Stadius. 

149.  Pallas. 

150.  Triesnecker. 

151.  Agrippa. 

152.  Arago. 

153.  Taruntius. 

154.  Apollonius. 


155.  Schubert. 

156.  Firmicus. 

157.  Silberschlag. 

158.  Hyginus. 

159.  Ukert. 

160.  Boscovich. 

161.  Ross. 

162.  Proclus. 

163.  Picard. 

164.  Condorcet. 

165.  Pliny  or 

Menelaus. 

167.  Manilius. 

168.  Erastothenes. 

169.  Gay  Lussac. 

170.  Tobias  Mayer. 

171.  Marius. 

172.  Olbers. 

173.  Vasco  de  Gama. 

174.  Seleucus. 

175.  Herodotus. 

176.  Aristarchus. 

177.  La  Hire. 

178.  Pytheas. 

179.  Bessel. 

180.  Vitruvius. 

181.  Maraldi. 

182.  Macrobius. 

183.  Cleomides. 

184.  Roemer. 

185.  Littrow. 

186.  Posidonius. 

187.  Geminus. 

188.  Linnaeus. 

189.  Autolycus. 

190.  Aristillus. 

191.  Archimedes. 


192.  Timocharis. 

193.  Lambert. 

194.  Diophantus. 

195.  Delisle. 

196.  Briggs. 

197.  Lichtenberg. 

199.  Calippus. 

200.  Cassini. 

201.  Gauss. 

202.  Messala. 

203.  Struve. 

204.  Mason. 

205.  Plana. 

206.  Burg. 

207.  Baily. 

208.  Eudoxus. 

209.  Aristotle. 

210.  Plato. 

211.  Pico. 

212.  Helicon. 

213.  Maupertuis. 

214.  Condamine. 

215.  Bianchini. 

216.  Sharp. 

217.  Mairan. 

218.  Gerard. 

219.  Repsold. 

220.  Pythagoras. 

221.  Fontenelle. 

222.  Timaeus. 

223.  Epigenes. 

224.  Gartner. 

225.  Thales. 

226.  Strabo. 

227.  Endymion. 

228.  Atlas. 

229.  Hercules. 


Oliver  C.  Farrington. 


[TO] 


The  Moon  13 


SOURCES   OF  ADDITIONAL  INFORMATION  ABOUT 
THE    MOON 

A  number  of  textbooks  and  popular  works  on  astronomy 
deal  more  or  less  fully  with  the  Moon.  Among  them  the 
following  may  be  mentioned. 

MouLTON,  Forest  Ray — Introduction  to  Astronomy.  Macmil- 
lan  &  Co.,  New  York.     1916.     577  pp. 

Young,  Charles  A. — A  Textbook  of  General  Astronomy.  Ginn 
&  Co.,  Boston.     1898.    630  pp. 

Todd,  David  P. — Stars  and  Telescopes.  Little,  Brown  &  Co., 
Boston.     1899.     419  pp. 

The  following  are  some  works  which  treat  exclusively  of 
the  Moon. 

Nasmyth,  James  and  Carpenter,  James — The  Moon.  John 
Murray,  London.  1885.  213  pp.  25  "Woodburytype" 
plates  and  several  text  figures. 

Pickering,  William  H. — The  Moon.  Doubleday,  Page  &  Co., 
New  York.  1903.  Quarto.  103  pp.  and  many  full-sized 
plates. 

Proctor,  Richard  A. — The  Moon.  Longmans,  Green  &  Co., 
London.     1898.     314  pp. 

Gilbert,  Grove  K. — The  Moon's  Face.  Bulletin  of  the  Philos- 
ophical Society  of  Washington,  1892-93.  Vol.  12,  pp. 
241-292. 

Shaler,  Nathaniel  S. — A  Comparison  of  the  Features  of  the 
Earth  and  the  Moon.  Smithsonian  Contributions  to  Knowl- 
edge.    1907.     Vol.  34,  pp.  1-79.     25  plates. 


[71] 


N 


The  figures 


The  figures  refer  to  the 


CHART  OF  THE  MOON'S  SURFACE.      AFTER  NaSMYTH. 

vith  the  model  will  enable  the  readei 


2  the  different  features 


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